1. Field of the Invention
The present invention relates generally to a video signal converting system suitable for converting a video signal into a digitized signal, and is directed more particularly to a video signal converting system in which quantization noise signals produced when a video signal is quantized can be reduced.
2. Description of the Prior Art
In general, when a video signal is converted into a digitized signal, or digital signal, and transmitted and transmitted digitized signal is later converted back into an analog signal to reproduce a television picture, the points that, in the picture, correspond to quantized levels of the video signal during the horizontal period tend to be arranged in the horizontal direction as quantized noise signals which cause a longitudinal stripe pattern or longitudinal stripes in the reproduced picture.
It has previously been proposed to "wobble" the video signal, that is, to vary the amplitude of the video signal to be converted into a digitized signal. The purpose of doing so is to avoid the formation of the longitudinal stripe pattern. In that case, however, the S/N (signal to noise) ratio of the video signal is deteriorated, or impaired by wobbling the video signal.
It is possible to eliminate the quantized noise signals by increasing the bit number of conversion. However, this makes the whole the system more complicated to construct. Further, some of the quantized noise signals cannot be eliminated by merely increasing the bit number of conversion.